Aluminum porous body and method for producing aluminum porous body

ABSTRACT

An aluminum porous body has a skeleton with a three-dimensional network structure, in which the skeleton is formed of an aluminum layer containing aluminum carbide, and when the aluminum porous body is subjected to XRD measurement, diffraction peaks originating from aluminum carbide are detected at two peak positions in a 2θ range of 30.8° or more and 31.5° or less and a 2θ range of 31.6° or more and 32.3° or less.

TECHNICAL FIELD

The present disclosure relates to an aluminum porous body and a methodfor producing an aluminum porous body.

The present application claims priority to Japanese Patent ApplicationNo. 2017-075270 filed on Apr. 5, 2017, the entire contents of which areincorporated herein by reference.

BACKGROUND ART

Patent Literature 1 discloses that a polycrystalline aluminum filmformed by plating has improved hardness because of the presence ofaluminum carbide particles in boundaries of aluminum grains.

CITATION LIST Patent Literature

-   PTL 1: Japanese Unexamined Patent Application Publication No.    2016-000838

SUMMARY OF INVENTION

An aluminum porous body of the present disclosure is an aluminum porousbody having a skeleton with a three-dimensional network structure, inwhich the skeleton is formed of an aluminum layer containing aluminumcarbide, and when the aluminum porous body is measured by an X-raydiffraction method, diffraction peaks originating from aluminum carbideare detected at two peak positions in a 2θ range of 30.8° or more and31.5° or less and a 2θ range of 31.6° or more and 32.3° or less.

A method for producing an aluminum porous body according to the presentdisclosure is a method for producing the foregoing aluminum porous bodyof the present disclosure and includes a conductivity-impartingtreatment step of subjecting the surface of the skeleton of a resinousformed body to conductivity-imparting treatment to impart conductivity,the skeleton having a three-dimensional network structure, anelectrolytic treatment step of subjecting the resinous formed body afterthe conductivity-imparting treatment step to electrolytic treatment inan electrolyte solution to provide a resin structure throughelectrodeposition of aluminum on the surface of the skeleton, a resinremoval step of removing the resinous formed body to provide an aluminumporous body through removal of the resin structure by heat-treating theresin structure or by dissolving the resin structure with an acid or analkali, and a crystallization step, in which the electrolyte solutionused in the electrolytic treatment step contains, as components, (A) analuminum halide, (B) one or more compounds selected from the groupconsisting of alkylimidazolium halides, alkylpyridinium halides, andurea compounds, and (C) an additive containing a carbon atom, theadditive being to be incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, in which a molarmixing ratio of the component (A) to the component (B) is in the rangeof 1:1 to 3:1, and each of the resin-removing step and thecrystallization step is performed by heat-treating the resin structurein an atmosphere at 650° C. or higher and 680° C. or lower in a vacuumof 1.0×10⁻² Pa or less.

A method for producing an aluminum porous body according to the presentdisclosure is a method for producing the foregoing aluminum porous bodyof the present disclosure and includes a conductivity-impartingtreatment step of subjecting the surface of the skeleton of a resinousformed body to conductivity-imparting treatment to impart conductivity,the skeleton having a three-dimensional network structure, anelectrolytic treatment step of subjecting the resinous formed body afterthe conductivity-imparting treatment step to electrolytic treatment inan electrolyte solution to provide a resin structure throughelectrodeposition of aluminum on the surface of the skeleton, a resinremoval step of removing the resinous formed body to provide an aluminumporous body by removing the resin structure by heat-treating the resinstructure or by dissolving the resin structure with an acid or analkali, and a crystallization step, in which the electrolyte solutionused in the electrolytic treatment step contains, as components, (A) analuminum halide, (B) one or more compounds selected from the groupconsisting of alkylimidazolium halides, alkylpyridinium halides, andurea compounds, and (C) an additive containing a carbon atom, theadditive being to be incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, in which a molarmixing ratio of the component (A) to the component (B) is in the rangeof 1:1 to 3:1, the resin removal step is performed by dissolution andremoval, and the crystallization step is performed by heat-treating theresin structure in an atmosphere at 650° C. or higher and 680° C. orlower in a vacuum of 1.0×10⁻² Pa or less.

A method for producing an aluminum porous body according to the presentdisclosure is a method for producing the foregoing aluminum porous bodyof the present disclosure and includes a conductivity-impartingtreatment step of subjecting the surface of the skeleton of a resinousformed body to conductivity-imparting treatment to impart conductivity,the skeleton having a three-dimensional network structure, anelectrolytic treatment step of subjecting the resinous formed body afterthe conductivity-imparting treatment step to electrolytic treatment inan electrolyte solution to provide a resin structure throughelectrodeposition of aluminum on the surface of the skeleton, a resinremoval step of removing the resinous formed body to provide an aluminumporous body through removal of the resin structure by heat-treating theresin structure or by dissolving the resin structure with an acid or analkali, and a crystallization step, in which the electrolyte solutionused in the electrolytic treatment step contains, as components, (A) analuminum halide, (B) one or more compounds selected from the groupconsisting of alkylimidazolium halides, alkylpyridinium halides, andurea compounds, and (C) an additive containing a carbon atom, theadditive being to be incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, in which a molarmixing ratio of the component (A) to the component (B) is in the rangeof 1:1 to 3:1, the resin removal step is performed by heat-treating theresin structure at 400° C. or higher in an air atmosphere, and thecrystallization step is performed by heat-treating the resin structurein an atmosphere at 650° C. or higher and 680° C. or lower in a vacuumof 1.0×10⁻² Pa or less.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an enlarged fragmentary sectional view schematicallyillustrating an example of an aluminum porous body according to anembodiment of the present disclosure.

FIG. 2 is an enlarged fragmentary sectional view schematicallyillustrating an example of a state in which a conductive layer isdisposed on the surface of the skeleton of a resinous formed body.

FIG. 3 is a photograph of a urethane foam as an example of a resinousformed body having a skeleton with a three-dimensional networkstructure.

FIG. 4 is an enlarged fragmentary sectional view schematicallyillustrating an example of a state in which an aluminum layer isdisposed on the surface of a conductive layer disposed on the surface ofthe skeleton of a resinous formed body.

FIG. 5 is a spectrum illustrating the results of X-ray diffractionmeasurement of aluminum porous body No. 2 produced in an example.

FIG. 6 is a spectrum illustrating the results of X-ray diffractionmeasurement of aluminum porous body No. 8 produced in a comparativeexample.

FIG. 7 is a photograph of a cross-section of the skeleton of aluminumporous body No. 2, which is produced in an example, observed with anelectron microscope (SEM).

DESCRIPTION OF EMBODIMENTS Problem to be Solved by Present Disclosure

The skeleton of a metal porous body having a skeleton with athree-dimensional network structure is formed of the aluminum layerdescribed in Patent Literature 1, thereby improving the hardness of theskeleton of the metal porous body. However, there is a limit. To furtherimprove an aluminum porous body having a skeleton with athree-dimensional network structure, the inventors have conductedintensive studies by comparing the physical properties between analuminum porous body free from aluminum carbide in its skeleton and analuminum porous body containing aluminum carbide in its skeleton (aporous body having a skeleton formed of the aluminum layer described inPatent Literature 1).

It has been found that the aluminum porous body containing aluminumcarbide in its skeleton is improved in tensile strength owing to animprovement in the hardness of the skeleton but is decreased inelongation at break.

The present disclosure aims to provide an aluminum porous body havinghigh elongation at break and high hardness of its skeleton and aproduction method therefor.

Advantageous Effects of Present Disclosure

According to the present disclosure, it is possible to provide thealuminum porous body having high elongation at break and the skeletonwith high hardness and the production method therefor.

Description of Embodiments of Present Disclosure

First, embodiments of the present disclosure will be listed andexplained.

(1) An aluminum porous body according to an embodiment of the presentdisclosure has a skeleton with a three-dimensional network structure, inwhich the skeleton is formed of an aluminum layer containing aluminumcarbide, and when the aluminum porous body is measured by an X-raydiffraction method, diffraction peaks originating from aluminum carbideare detected at two peak positions in a 2θ range of 30.8° or more and31.5° or less and a 2θ range of 31.6° or more and 32.3° or less.

According to the embodiment of the disclosure described in (1) above, itis possible to provide the aluminum porous body having high elongationat break and the skeleton with high hardness.

(2) In the aluminum porous body described in (1), the skeletonpreferably has an aluminum carbide content of 0.5% or more by mass and1.8% or less by mass.

According to the embodiment of the disclosure described in (2) above, itis possible to provide the aluminum porous body having the skeleton withhigher hardness.

(3) The aluminum porous body described in (1) or (2) preferably has atensile strength of 0.8 MPa or more.

According to the embodiment of the disclosure described in (3) above, itis possible to provide the aluminum porous body having high tensilestrength.

(4) The aluminum porous body described in any one of (1) to (3) abovepreferably has an elongation at break of 1.6% or more.

According to the embodiment of the disclosure described in (4) above, itis possible to provide the aluminum porous body having high elongationat break.

(5) In the aluminum porous body described in any one of (1) to (4)above, the skeleton preferably has a hardness H of 0.5 GPa or more and2.0 GPa or less, the hardness being measured with a nanoindenter.

According to the embodiment of the disclosure described in (5) above, itis possible to provide the aluminum porous body having the skeleton withhigh hardness.

(6) In the aluminum porous body described in any one of (1) to (5)above, grains of the aluminum layer constituting the skeleton preferablyhave a number-average grain size of 2.0 μm or more and 10.0 μm or less.

According to the embodiment of the disclosure described in (6) above, itis possible to provide the aluminum porous body having higher elongationat break.

(7) A method for producing an aluminum porous body according to thepresent disclosure is a method for producing the foregoing aluminumporous body of the present disclosure and includes aconductivity-imparting treatment step of subjecting the surface of theskeleton of a resinous formed body to conductivity-imparting treatmentto impart conductivity, the skeleton having a three-dimensional networkstructure, an electrolytic treatment step of subjecting the resinousformed body after the conductivity-imparting treatment step toelectrolytic treatment in an electrolyte solution to provide a resinstructure through electrodeposition of aluminum on the surface of theskeleton, a resin removal step of removing the resinous formed body toprovide an aluminum porous body through removal of the resin structureby heat-treating the resin structure or by dissolving the resinstructure with an acid or an alkali, and a crystallization step, inwhich the electrolyte solution used in the electrolytic treatment stepcontains, as components, (A) an aluminum halide, (B) one or morecompounds selected from the group consisting of alkylimidazoliumhalides, alkylpyridinium halides, and urea compounds, and (C) anadditive containing a carbon atom, the additive being to be incorporatedinto aluminum electrodeposited on the surface of the skeleton of theresinous formed body, in which a molar mixing ratio of the component (A)to the component (B) is in the range of 1:1 to 3:1, and each of theresin-removing step and the crystallization step is performed byheat-treating the resin structure in an atmosphere at 650° C. or higherand 680° C. or lower in a vacuum of 1.0×10⁻² Pa or less.(8) A method for producing an aluminum porous body according to thepresent disclosure is a method for producing the foregoing aluminumporous body of the present disclosure and includes aconductivity-imparting treatment step of subjecting the surface of theskeleton of a resinous formed body to conductivity-imparting treatmentto impart conductivity, the skeleton having a three-dimensional networkstructure, an electrolytic treatment step of subjecting the resinousformed body after the conductivity-imparting treatment step toelectrolytic treatment in an electrolyte solution to provide a resinstructure through electrodeposition of aluminum on the surface of theskeleton, a resin removal step of removing the resinous formed body toprovide an aluminum porous body by removing the resin structure byheat-treating the resin structure or by dissolving the resin structurewith an acid or an alkali; and a crystallization step, in which theelectrolyte solution used in the electrolytic treatment step contains,as components, (A) an aluminum halide, (B) one or more compoundsselected from the group consisting of alkylimidazolium halides,alkylpyridinium halides, and urea compounds, and (C) an additivecontaining a carbon atom, the additive being to be incorporated intoaluminum electrodeposited on the surface of the skeleton of the resinousformed body, in which a molar mixing ratio of the component (A) to thecomponent (B) is in the range of 1:1 to 3:1, the resin removal step isperformed by dissolution and removal, and the crystallization step isperformed by heat-treating the resin structure in an atmosphere at 650°C. or higher and 680° C. or lower in a vacuum of 1.0×10⁻² Pa or less.(9) A method for producing an aluminum porous body according to thepresent disclosure is a method for producing the foregoing aluminumporous body of the present disclosure and includes aconductivity-imparting treatment step of subjecting the surface of theskeleton of a resinous formed body to conductivity-imparting treatmentto impart conductivity, the skeleton having a three-dimensional networkstructure, an electrolytic treatment step of subjecting the resinousformed body after the conductivity-imparting treatment step toelectrolytic treatment in an electrolyte solution to provide a resinstructure through electrodeposition of aluminum on the surface of theskeleton, a resin removal step of removing the resinous formed body toprovide an aluminum porous body through removal of the resin structureby heat-treating the resin structure or by dissolving the resinstructure with an acid or an alkali, and a crystallization step, theelectrolyte solution used in the electrolytic treatment step contains,as components, (A) an aluminum halide, (B) one or more compoundsselected from the group consisting of alkylimidazolium halides,alkylpyridinium halides, and urea compounds, and (C) an additivecontaining a carbon atom, the additive being to be incorporated intoaluminum electrodeposited on the surface of the skeleton of the resinousformed body, in which a molar mixing ratio of the component (A) to thecomponent (B) is in the range of 1:1 to 3:1, the resin removal step isperformed by heat-treating the resin structure at 400° C. or higher inan air atmosphere, and the crystallization step is performed byheat-treating the resin structure in an atmosphere at 650° C. or higherand 680° C. or lower in a vacuum of 1.0×10⁻² Pa or less.

According to the embodiment of the disclosure described in (7) or (8),it is possible to provide the method for producing the aluminum porousbody having high elongation at break and the skeleton with highhardness.

Details of Embodiments of Present Disclosure

Specific examples of an aluminum porous body and a production methodtherefor according to embodiments of the present disclosure will bedescribed below. The present disclosure is not limited to these examplesbut is defined by the following claims, and is intended to include anymodifications within the scope and meaning equivalent to the scope ofthe claims.

<Aluminum Porous Body>

An aluminum porous body according to an embodiment of the presentdisclosure has a skeleton with a three-dimensional network structure.

FIG. 1 is an enlarged schematic view in which the cross-section of anexample of an aluminum porous body according to an embodiment of thepresent disclosure is enlarged. As illustrated in FIG. 1, in an aluminumporous body 10, a skeleton 12 is formed of an aluminum layer 11containing aluminum carbide. The interior 13 of the skeleton 12 ishollow. The aluminum porous body 10 has a communicating pore. A porousportion 14 is defined by the skeleton 12. The aluminum layer 11 containshigh-crystallinity aluminum carbide; thus, the aluminum porous body 10has high elongation at break and the skeleton with high hardness.

As described above, in the aluminum porous body according to theembodiment of the present disclosure, the aluminum layer constitutingthe skeleton contains high-crystallinity aluminum carbide. Thus, whenthe aluminum porous body according to the embodiment of the presentdisclosure is measured by an X-ray diffraction (XRD) method, diffractionpeaks originating from aluminum carbide are detected at two peakpositions in a 2θ range of 30.8° or more and 31.5° or less and a 2θrange of 31.6° or more and 32.3° or less. When an aluminum porous bodycontaining conventional aluminum carbide is measured by XRD, only asingle diffraction peak originating from the aluminum carbide isdetected because the aluminum carbide has poor crystallinity and isamorphous. In contrast, in the aluminum porous body according to theembodiment of the present disclosure, the two diffraction peaks aredetected in the ranges above because the aluminum carbide contained inthe aluminum layer constituting the skeleton has very highcrystallinity. Additionally, because of the high-crystallinity aluminumcarbide, the aluminum porous body according to the embodiment of thepresent disclosure has higher elongation at break than the conventionalaluminum porous body.

The XRD measurement may be performed using CuKα radiation underexcitation conditions of 45 kV and 40 mA.

In the aluminum porous body according to the embodiment of the presentdisclosure, the skeleton preferably has an aluminum carbide content of0.5% or more by mass and 1.8% or less by mass. At an aluminum carbidecontent of 0.5% or more by mass, the skeleton has high hardness, thusleading to the aluminum porous body having high strength (tensilestrength). At an aluminum carbide content of 1.8% or less by mass, adecrease in elongation at break can be inhibited. From these points ofview, the skeleton of the aluminum porous body more preferably has analuminum carbide content of 0.8% or more by mass and 1.2% or less bymass, even more preferably 0.9% or more by mass and 1.1% or less bymass.

The aluminum carbide content of the skeleton of the aluminum porous bodycan be calculated from the ratio of a diffraction peak originating fromaluminum to a diffraction peak originating from aluminum carbidedetected when the aluminum porous body is measured by an X-raydiffraction method. In the case where the skeleton of an aluminum porousbody contains a component other than aluminum or aluminum carbide andwhere a diffraction peak originating from the component is detected, thealuminum carbide content may be calculated from the ratio of adiffraction peak originating from the component to the diffraction peakoriginating from aluminum to the diffraction peak originating fromaluminum carbide.

The aluminum porous body preferably has a tensile strength of 0.8 MPa ormore. The tensile strength of the aluminum porous body refers to a valueobtained by applying tensile stress to the aluminum porous body (testpiece) and dividing the maximum stress applied to a test piece at thetime of fracture of the test piece by the initial cross-sectional areaof the test piece. Note that because the test piece is formed of thealuminum porous body, the cross-sectional area is defined as an apparentcross-sectional area. The test piece may have a shape measuring 20 mm inwidth, 100 mm in length, and 60 mm in gauge length when both ends arefixed by grips (length excluding tabs for gripping).

The aluminum porous body has a tensile strength of 0.8 MPa or more andthus has high strength. An increase in the coating weight of thealuminum porous body tends to increase the tensile strength of thealuminum porous body. In the aluminum porous body according to theembodiment of the present disclosure, for example, when the coatingweight of the aluminum porous body is 135 g/m² or more, the aluminumporous body can have a tensile strength of 0.8 MPa or more.

The coating weight of the aluminum porous body refers to the mass of thealuminum porous body per apparent unit area.

Higher tensile strength of the aluminum porous body is preferred. Thealuminum porous body more preferably has a tensile strength of 1.0 MPaor more, even more preferably 1.2 MPa or more.

The aluminum porous body preferably has an elongation at break of 1.6%or more. The elongation at break of the aluminum porous body refers to,in the case of measuring the tensile strength of the aluminum porousbody, the proportion (percentage) of the length of the test piece(length between the grips) at the time of application of the maximumstress to the gauge length of the aluminum porous body (test piece)before application of tensile stress.

In the case of the aluminum porous body having an elongation at break of1.6% or more, a crack or the like is not easily formed in the aluminumporous body when the aluminum porous body is deformed. An increase inthe coating weight of the aluminum porous body tends to increase theelongation at break of the aluminum porous body. In the aluminum porousbody according to the embodiment of the present disclosure, for example,when the coating weight of the aluminum porous body is 135 g/m² or more,the aluminum porous body can have an elongation at break of 1.6% ormore.

Higher elongation at break of the aluminum porous body is preferred. Thealuminum porous body more preferably has an elongation at break of 1.8%or more, even more preferably 2.0% or more.

The skeleton of the aluminum porous body preferably has a hardness H of0.5 GPa or more and 2.0 GPa or less, the hardness being measured with ananoindenter.

When the skeleton of the aluminum porous body has a hardness H of 0.5GPa or more, the aluminum porous body has the skeleton with highhardness. When the skeleton of the aluminum porous body has a hardness Hof 2.0 GPa or less, the aluminum porous body has high elongation atbreak. From these points of view, the skeleton of the aluminum porousbody more preferably has a hardness H of 0.8 GPa or more and 1.5 GPa orless, even more preferably 0.9 GPa or more and 1.2 GPa or less.

In the aluminum porous body according to the embodiment of the presentdisclosure, grains of the aluminum layer constituting the skeletonpreferably have a number-average grain size of 2.0 μm or more and 10.0μm or less. The number-average grain size of the grains of the aluminumlayer refers to the average grain size of freely-selected 10 grainsobserved when a cross section of the skeleton of the aluminum porousbody is observed with an electron microscope (SEM). When the number ofgrains observed in one field of view is less than 10, observation may becontinued in a different field of view to measure the grain size of atotal of 10 grains. The grain size of a grain refers to the average ofthe longest diameter and the shortest diameter of the grain observedwith SEM.

When the grains of the aluminum layer have a number-average grain sizeof 2.0 μm or more, the aluminum porous body has high elongation atbreak. When the grains of the aluminum layer have a number-average grainsize of 10.0 μm or less, high hardness is provided. From these points ofview, the grains of the aluminum layer constituting the skeleton of thealuminum porous body more preferably have a number-average grain size of4.0 μm or more and 8.0 μm or less, even more preferably 5.0 μm or moreand 7.5 μm or less.

The porosity, the average pore diameter, and the thickness of thealuminum porous body may be appropriately selected in accordance withthe application of the aluminum porous body. For example, in the casewhere the aluminum porous body is used as an electrode (collector) of abattery, a thin aluminum porous body with a small average pore diameteris preferred. In the case of the aluminum porous body is used for heatdissipation, a thick aluminum porous body with a large average porediameter is preferred.

The porosity of the aluminum porous body refers to the percentage of thevolume of the internal space (porous portion) of the aluminum porousbody with respect to the apparent volume.

The average pore diameter of the aluminum porous body refers to thereciprocal of the number of cells (cells/inch) defined by the skeletonof the aluminum porous body.

<Method for Producing Aluminum Porous Body>

A method for producing an aluminum porous body according to anembodiment of the present disclosure is a method for producing thealuminum porous body according to the embodiment of the presentdisclosure.

[Method for Producing Aluminum Porous Body According to FirstEmbodiment]

A method for producing an aluminum porous body according to a firstembodiment includes a conductivity-imparting treatment step, anelectrolytic treatment step, a resin removal step, and a crystallizationstep. These steps will be described in detail below.

—Conductivity-Imparting Treatment Step—

The conductivity-imparting treatment step is a step of providing aresinous formed body having a skeleton with a three-dimensional networkstructure and subjecting the surface of the skeleton toconductivity-imparting treatment to impart conductivity. For example,conductivity can be imparted to the surface of the skeleton of theresinous formed body by forming a conductive layer so as to cover thesurface of the skeleton of the resinous formed body. FIG. 2 is anenlarged fragmentary sectional view schematically illustrating anexample of a state in which a conductive layer 16 is disposed on thesurface of the skeleton of a resinous formed body 15.

(Resinous Formed Body)

When an aluminum porous body according to the embodiment of the presentdisclosure is produced, a resinous formed body having a skeleton with athree-dimensional network structure (hereinafter, also referred tosimply as “resinous formed body”) is used as a base. As illustrated inFIG. 2, the resinous formed body 15 has a communicating pore, and theporous portion 14 is defined by the skeleton. As the resinous formedbody 15, for example, a resin foam, a nonwoven fabric, felt, or a wovenfabric may be used. These may be used in combination, as needed. Thematerial of the resinous formed body 15 may be any material that can beremoved by heat treatment after the surface of the skeleton is platedwith aluminum. In particular, in the case of the resinous formed body 15having a sheet-like shape, a flexible material is preferred in terms ofhandling because if the rigidity is too high, the skeleton will break.

As the resinous formed body 15 having the skeleton with thethree-dimensional network structure, a resin foam is preferably used.The resin foam may be any porous resin foam. A known or commerciallyavailable porous resin foam may be used. For example, a urethane foam ora styrene foam may be used. Among these, in particular, the urethanefoam is preferred in view of high porosity. FIG. 3 is a photograph of afoamed urethane resin.

Because aluminum is electro-deposited on the surface of the skeleton ofthe resinous formed body 15 to form the skeleton of the aluminum porousbody, the porosity, the average pore diameter, and the thickness of thealuminum porous body are substantially equal to the porosity, theaverage pore diameter, and the thickness of the resinous formed body 15.Thus, the porosity, the average pore diameter, and the thickness of theresinous formed body 15 may be appropriately selected in accordance withthe porosity, the average pore diameter, and the thickness of the targetaluminum porous body. The porosity and the average pore diameter of theresinous formed body 15 are defined the same as the porosity and theaverage pore diameter of the aluminum porous body.

(Conductivity-Imparting Treatment)

A method for subjecting the surface of the skeleton of the resinousformed body 15 to conductivity-imparting treatment is not particularlylimited as long as it is a method by which the conductive layer 16 canbe formed on the surface of the skeleton of the resinous formed body 15.Examples of the material constituting the conductive layer 16 includemetals such as nickel, titanium, and stainless steel and carbon powderssuch as amorphous carbon, e.g., carbon black, and graphite. Among these,in particular, carbon powders are preferred. Carbon black is morepreferred. In the case where the conductive layer 16 is formed using anamorphous carbon or a carbon powder other than metal, the conductivelayer 16 is also removed in the resin removal step described below.

Regarding specific examples of the conductivity-imparting treatment, forexample, in the case of using nickel, electroless plating treatment andsputtering treatment are preferably exemplified. In the case of using ametal such as titanium or stainless steel or a material such as carbonblack or graphite, an example of a preferred method is treatment ofapplying a mixture, obtained by adding a binder to the fine powder ofthe material, to the surface of the skeleton of the resinous formed body15.

As the electroless plating treatment using nickel, for example, theresinous formed body 15 may be immersed in a known electrolessnickel-plating bath such as an aqueous solution of nickel sulfatecontaining sodium hypophosphite serving as a reductant. The resinousformed body 15 may be immersed in an activation liquid containing a verysmall amount of palladium ions (cleaning liquid, available from JapanKanigen Co., Ltd.) before immersion in the plating bath, as needed.

The sputtering treatment using nickel may be performed as follows: Forexample, after the resinous formed body 15 is attached to a substrateholder, a direct-current voltage is applied between the holder and atarget (nickel) while introducing an inert gas. The inert gas is ionizedand collides with nickel to eject nickel particles. The ejected nickelparticles are deposited on the surface of the skeleton of the resinousformed body 15.

The conductive layer 16 may be continuously formed so as to cover thesurface of the skeleton of the resinous formed body 15. The coatingweight of the conductive layer 16 is preferably, but not necessarily,1.0 g/m² or more and 30 g/m² or less, more preferably 5.0 g/m² or moreand 20 g/m² or less, even more preferably 7.0 g/m² or more and 15 g/m²or less.

The coating weight of the conductive layer refers to the mass of theconductive layer per apparent unit area of the resinous formed bodyincluding the conductive layer formed on the surface of the skeletonthereof.

—Electrolytic Treatment Step—

The electrolytic treatment step is a step of subjecting the resinousformed body to which conductivity has been imparted to electrolytictreatment in an electrolyte solution to provide a resin structurethrough electrodeposition of aluminum on the surface of the skeleton.FIG. 4 is an enlarged fragmentary sectional view schematicallyillustrating an example of a state in which the aluminum layer 11 isdisposed on the surface of the conductive layer 16 disposed on thesurface of the skeleton of the resinous formed body 15.

(Electrolyte Solution)

As the electrolyte solution, a mixture of a molten salt and component(C) serving as an additive is used, the molten salt containing component(A) and component (B).

Component (A): an aluminum halideComponent (B): one or more compounds selected from the group consistingof alkylimidazolium halides, alkylpyridinium halides, and urea compoundsComponent (C): an additive containing a carbon atom, the additive beingto be incorporated into aluminum electrodeposited on the surface of theskeleton of the resinous formed body

The electrolyte solution may contain other components as incidentalimpurities. The electrolyte solution may intentionally contain othercomponents as long as the advantageous effects of the method forproducing an aluminum porous body according to the embodiment of thepresent disclosure, in which the aluminum porous body having highelongation at break and having the skeleton with high hardness can beproduced, are not impaired.

As the aluminum halide serving as the component (A), any aluminum halidethat forms a molten salt at about 110° C. or lower when mixed with thecomponent (B) may be appropriately used. Examples thereof includealuminum chloride (AlCl₃), aluminum bromide (AlBr₃), and aluminum iodide(AlI₃). Among these, aluminum chloride is most preferred.

As the alkylimidazolium halide serving as the component (B), anyalkylimidazolium halide that forms a molten salt at about 110° C. orlower when mixed with the component (A) may be appropriately used.

Examples thereof include imidazolium chloride having alkyl groups (eachhaving 1 to 5 carbon atoms) at the 1- and 3-positions, imidazoliumchloride having alkyl groups (each having 1 to 5 carbon atoms) at the1-, 2-, and 3-positions, and imidazolium iodide having alkyl groups(each having 1 to 5 carbon atoms) at the 1- and 3-positions.

Specific examples thereof include 1-ethyl-3-methylimidazolium chloride(EMIC), 1-butyl-3-methylimidazolium chloride (BMIC), and1-methyl-3-propylimidazolium chloride (MPIC). Among these,1-ethyl-3-methylimidazolium chloride (EMIC) can be most preferably used.

As the alkylpyridinium halide serving as the component (B), anyalkylpyridinium halide that forms a molten salt at about 110° C. orlower when mixed with the component (A) may be appropriately used.

Examples thereof include 1-butylpyridinium chloride (BPC),1-ethylpyridinium chloride (EPC), and 1-butyl-3-methylpyridiniumchloride (BMPC). Among these, 1-butylpyridinium chloride is mostpreferred.

The urea compound serving as the component (B) refers to urea or itsderivative. Any urea compound that forms a molten salt at about 110° C.or lower when mixed with the component (A) may be appropriately used.

For example, a compound represented by formula (1) may be preferablyused:

where in formula (1), each R is a hydrogen atom, an alkyl group having 1to 6 carbon atoms, or a phenyl group, and Rs may be the same ordifferent.

Among the urea compounds, urea or dimethylurea may be particularlypreferably used.

In the electrolyte solution, when the molar mixing ratio of thecomponent (A) to the component (B) is in the range of 1:1 to 3:1, theelectrolyte solution (plating solution) is suitable forelectrodeposition of aluminum on the surface of the skeleton of theresinous formed body.

If the molar ratio of the component (A) is less than 1 when thecomponent (B) is 1, an electrodeposition reaction of aluminum does notoccur. If the molar ratio of the component (A) is more than 3 when thecomponent (B) is 1, aluminum chloride precipitates in the electrolytesolution and is incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, thereby degradingthe quality of aluminum.

The additive serving as the component (C) is not particularly limited aslong as it contains a carbon atom and is to be incorporated intoaluminum electrodeposited on the surface of the skeleton of the resinousformed body. When the additive containing a carbon atom is incorporatedinto aluminum, the carbon atom contained in the additive reacts withaluminum to form aluminum carbide in the resin removal step or thecrystallization step described below.

The additive is preferably, for example, a compound described below.

The additive is preferably one or more selected from the groupconsisting of 1,10-phenanthrolinium chloride monohydrate,1,10-phenanthroline monohydrate, 1,10-phenanthroline, 3-benzoylpyridine,pyrazine, 1,3,5-triazine, 1,2,3-benzotriazole, acetophenone,acetylpyridine, 3-pyridinecarboxaldehyde, N,N′-methylenebis(acrylamide),methyl nicotinate, nicotinoyl chloride hydrochloride, and isoniazid.

The concentration of the component (C) in the electrolyte solution maybe appropriately changed in accordance with the type of the component(C) used.

For example, when 1,10-phenanthrolinium chloride monohydrate,1,3,5-triazine, acetylpyridine, 3-pyridinecarboxaldehyde,N,N′-methylenebis(acrylamide), or nicotinoyl chloride hydrochloride isused as the component (C), the concentration of the component (C) in theelectrolyte solution is preferably 0.03 g/L or more and 7.5 g/L or less.In consideration of the amount of the component (C) incorporated intothe aluminum layer and the magnitude of residual stress in the aluminumlayer, the concentration of the component (C) in the electrolytesolution is more preferably 0.1 g/L or more and 5.0 g/L or less, evenmore preferably 0.3 g/L or more and 1.5 g/L or less.

When 1,10-phenanthroline monohydrate, 3-benzoylpyridine, pyrazine,1,2,3-benzotriazole, methyl nicotinate, or isoniazid is used as thecomponent (C), the concentration of the component (C) in the electrolytesolution is preferably 0.05 g/L or more and 7.5 g/L or less. Inconsideration of the amount of the component (C) incorporated into thealuminum layer and the magnitude of residual stress in the aluminumlayer, the concentration of the component (C) in the electrolytesolution is more preferably 0.1 g/L or more and 2.0 g/L or less, evenmore preferably 0.3 g/L or more and 1.0 g/L or less.

When 1,10-phenanthroline monohydrate and acetophenone is used as thecomponent (C), the concentration of the component (C) in the electrolytesolution is preferably 0.1 g/L or more and 10 g/L or less. Inconsideration of the amount of the component (C) incorporated into thealuminum layer and the magnitude of residual stress in the aluminumlayer, the concentration of the component (C) in the electrolytesolution is more preferably 0.25 g/L or more and 7 g/L or less, evenmore preferably 2.5 g/L or more and 5 g/L or less.

(Electrolytic Treatment Condition)

The electrolytic treatment (molten salt electrolysis) can be performedas described below.

The resinous formed body after the conductivity-imparting treatment stepand aluminum are arranged opposite to each other in the electrolytesolution. The resinous formed body is connected to the cathode side of arectifier. The aluminum is connected to the anode side. A voltage isapplied between both electrodes.

Here, the molten salt electrolysis is preferably performed bycontrolling the current through application of the voltage in such amanner that the current density is 30 mA/cm² or more and 60 mA/cm² orless. A current density of 30 mA/cm² or more results in the formation ofa smooth aluminum layer. At a current density of 60 mA/cm² or less, itis possible to inhibit the formation of scorch marks in which thealuminum layer on the surface of the skeleton of the resinous formedbody turns black. From these points of view, the current density ispreferably 30 mA/cm² or more and 50 mA/cm² or less, even more preferably35 mA/cm² or more and 45 mA/cm² or less.

The current density is calculated on the basis of the apparent area ofthe surface of the resinous formed body on which the aluminum layer isformed.

—Resin Removal Step—

The resin removal step is a step of removing the resin structure thathas been formed in the electrolytic treatment step to provide analuminum porous body. When the conductive layer 16 disposed on thesurface of the skeleton of the resinous formed body 15 is composed ofamorphous carbon or a carbon powder other than metal, the conductivelayer 16 is also removed by the heat treatment. For example, in anexample of a resin structure illustrated in FIG. 4, the resinous formedbody 15 and the conductive layer 16 are removed by the heat treatment,leaving the aluminum layer 11. Thereby, the aluminum porous body 10having the skeleton with the three-dimensional network structure isprovided (see FIG. 1). When the conductive layer 16 of the resinstructure is composed of a metal, the heat treatment of the resinstructure causes the metal constituting the conductive layer 16 todiffuse into the aluminum layer 11 or to be alloyed with aluminum.

—Crystallization Step—

In the crystallization step, the aluminum porous body may beheat-treated in an atmosphere at 650° C. or higher and 680° C. or lowerin a vacuum of 1.0×10⁻² Pa or less. The heat treatment time may be about1 hour or more and about 60 hours or less. In the production of thealuminum porous body according to the first embodiment, the resinremoval step and the crystallization step are preferably performed undersame conditions.

The component (C) serving as the additive used in the electrolytictreatment step is incorporated in the aluminum layer 11 before the heattreatment of the resin structure. Because the component (C) contains acarbon atom, the heat treatment of the resin structure allows aluminumto react with the component (C) to form aluminum carbide. When the resinstructure is heat-treated in an atmosphere at 650° C. or higher and 680°C. or lower in a vacuum of 1.0×10⁻² Pa or less, high-crystallinityaluminum carbide is formed. When the aluminum porous body having theskeleton formed of the aluminum layer 11 containing thehigh-crystallinity aluminum carbide is measured by an X-ray diffractionmethod, diffraction peaks originating from aluminum carbide are detectedat two peak positions in a 2θ range of 30.8° or more and 31.5° or lessand a 2θ range of 31.6° or more and 32.3° or less.

When the atmosphere in which the heat treatment is performed has avacuum of more than 1.0×10⁻² Pa, high-crystallinity aluminum carbidecannot be formed in the aluminum layer 11. The atmosphere in which theheat treatment is performed preferably has a higher vacuum (lowerpressure), more preferably has a vacuum of 1.0×10⁻³ Pa or less, evenmore preferably 1.0×10⁻⁴ Pa or less. In a vacuum of more than 1.0×10⁻¹Pa, carbon in the coating film is partially oxidized into carbondioxide, thus failing to form high-crystallinity aluminum carbide.

When the heat-treatment temperature of the resin structure is lower than650° C., high-crystallinity aluminum carbide cannot be formed in thealuminum layer 11. When the heat-treatment temperature is higher than680° C., the aluminum layer 11 constituting the skeleton melts. Thus,the heat-treatment temperature of the resin structure is more preferably660° C. or higher and 675° C. or lower, even more preferably 665° C. orhigher and 670° C. or lower.

The heat-treatment time of the resin structure is preferably 1 hour ormore and 60 hours or less. When the heat-treatment time is 1 hour ormore, the resinous formed body and the conductive layer can besufficiently burned, and the reaction between aluminum and the component(C) can proceed to form aluminum carbide in the aluminum layer. When theheat-treatment time is 60 hours or less, it is possible to inhibitexcessive oxidation of the aluminum layer 11. From these points of view,the heat-treatment time of the resin structure is more preferably 6hours or more and 48 hours or less, even more preferably 12 hours ormore and 36 hours or less.

[Method for Producing Aluminum Porous Body According to SecondEmbodiment]

A method for producing an aluminum porous body according to a secondembodiment includes a conductivity-imparting treatment step, anelectrolytic treatment step, a resin removal step, and a crystallizationstep.

The conductivity-imparting treatment step and the electrolytic treatmentstep in the method for producing an aluminum porous body according tothe second embodiment can be performed in the same ways as theconductivity-imparting treatment step and the electrolytic treatmentstep in the method for producing an aluminum porous body according tothe first embodiment described above; thus, descriptions are omitted.

—Resin Removal Step—

The resin removal step is a step of removing the resinous formed bodyfrom the resin structure formed in the electrolytic treatment step toprovide an aluminum porous body. In the method for producing an aluminumporous body according to the second embodiment, a method for removingthe resinous formed body is not particularly limited. Examples thereofinclude heat treatment and removal by dissolution with an acid or analkali. The heat treatment may be performed in an air atmosphere at 400°C. or higher, unlike the heat treatment in high vacuum at a hightemperature for the aluminum porous body according to the firstembodiment. The heat-treatment time here is preferably within 1 hour,more preferably within 30 minutes.

Regarding the acid or the alkali, for example, the removal may beperformed by immersing the resin structure in hydrochloric acid (HCl),sulfuric acid (H₂SO₄), sodium hydroxide (NaOH), dilute nitric acid(HNO₃), concentrated nitric acid, or the like.

—Crystallization Step—

The crystallization step may be performed under the same conditions asthose in the resin removal step in the method for producing an aluminumporous body according to the first embodiment. That is, the aluminumporous body may be heat-treated in an atmosphere at 650° C. or higherand 680° C. or lower in a vacuum of 1.0×10⁻² Pa or less. Theheat-treatment time may be about 1 hour or more and 60 hours or less.

The component (C) serving as the additive used in the electrolytictreatment step is contained in the aluminum layer of the aluminum porousbody after the resin removal step. In the case where the resin removalstep is performed by heat treatment in air or a molten salt, aluminumcarbide formed by reaction of aluminum with a carbon atom originatingfrom the component (C) is contained in the aluminum layer. However, thealuminum carbide has low crystallinity. Thus, when the aluminum porousbody is measured by an X-ray diffraction method, only one diffractionpeak originating from aluminum carbide can be detected.

In the method for producing an aluminum porous body according to thesecond embodiment, the crystallization step is performed after the resinremoval step, thereby enabling the crystallinity of aluminum carbide inthe aluminum layer to be increased. In the case where the component (C)unreacted with aluminum is contained in the aluminum layer of thealuminum porous body after the resin removal step, by performing thecrystallization step, aluminum and the component (C) can be reacted toform high-crystallinity aluminum carbide in the aluminum layer.

EXAMPLES

While the present disclosure will be described in more detail below byexamples, these examples are illustrative, an aluminum porous body and aproduction method therefor of the present disclosure are not limitedthereto. The scope of the present disclosure is defined by the followingclaims, and is intended to include any modifications within the scopeand meaning equivalent to the scope of the claims.

Example 1 <Conductivity-Imparting Treatment Step>

A polyurethane sheet having a thickness of 1.5 mm was used as a resinousformed body having a skeleton with a three-dimensional networkstructure. The resinous formed body had a porosity of 96% and an averagepore diameter of 450 μm.

A conductivity-imparting treatment was performed by immersing thepolyurethane sheet in a carbon suspension and drying the polyurethanesheet to form a conductive layer on the surface of the skeleton of thepolyurethane sheet. Regarding components of the carbon suspension, thesuspension contained 25% graphite and carbon black and contained a resinbinder, a penetrant, and an antifoaming agent. The carbon black had aparticle size of 0.5 μm.

<Electrolytic Treatment Step> (Electrolyte Solution)

Aluminum chloride (AlCl₃) was used as component (A), and1-ethyl-3-methylimidazolium chloride (EMIC) was used as component (B).The component (A) and the component (B) were mixed in a molar ratio of2:1 to prepare a molten salt. Then 1,10-phenanthrolinium chloridemonohydrate was added as component (C) to the molten salt in aconcentration of 0.5 g/L, thereby providing an electrolyte solution.

(Molten Salt Electrolysis)

Molten salt electrolysis was performed in the electrolyte solutionprovided above in such a manner that the polyurethane sheet that hadbeen subjected to the conductivity-imparting treatment was used as acathode and an aluminum plate having a purity of 99.99% was used as ananode. Thereby, aluminum was electrodeposited on the surface of theskeleton of the polyurethane sheet to provide a resin structure. Thetemperature of the electrolyte solution was 45° C. The current densitywas 6.0 A/dm².

<Resin Removal Step and Crystallization Step>

The resin structure provided above was heat-treated at 660° C. for 24hours in a vacuum of 1.0×10⁻² Pa to remove the polyurethane sheet and aconductive layer from the resin structure, thereby providing aluminumporous body No. 1.

Example 2

Aluminum porous body No. 2 was produced as in Example 1, except that theheat-treatment temperature of the resin removal step and thecrystallization step was 665° C.

Example 3

Aluminum porous body No. 3 was produced as in Example 1, except that theheat-treatment temperature of the resin removal step and thecrystallization step was 670° C.

Example 4

Aluminum porous body No. 4 was produced as in Example 1, except that thepressure of the atmosphere in the resin removal step and thecrystallization step was 4.0×10⁻³ Pa.

Example 5 <Conductivity-Imparting Treatment Step>

A resinous formed body identical to the resinous formed body used inExample 1 was provided. A conductivity-imparting treatment step wasperformed as in Example 1.

<Electrolytic Treatment Step>

An electrolytic treatment step was performed as in Example 1 to providea resin structure.

<Resin Removal Step>

The resin structure provided above was heat-treated at 500° C. for 20minutes in air to remove a polyurethane sheet and a conductive layerfrom the resin structure, thereby providing an aluminum porous body.

<Crystallization Step>

The aluminum porous body provided above was heat-treated at 660° C. for24 hours in a vacuum of 1.0×10⁻² Pa to provide aluminum porous body No.5.

Example 6 <Conductivity-Imparting Treatment Step>

A resinous formed body identical to the resinous formed body used inExample 1 was provided. A conductivity-imparting treatment step wasperformed as in Example 1.

<Electrolytic Treatment Step>

An electrolytic treatment step was performed as in Example 1 to providea resin structure.

<Resin Removal Step>

The resin structure provided above was immersed in 69% by massconcentrated nitric acid at 25° C. for 10 minutes to remove apolyurethane sheet and a conductive layer from the resin structure,thereby providing an aluminum porous body.

<Crystallization Step>

The aluminum porous body provided above was heat-treated at 660° C. for24 hours in a vacuum of 1.0×10⁻² Pa to provide aluminum porous body No.6.

Comparative Example 1

Aluminum porous body No. 7 was produced as in Example 1, except that theheat treatment in each of the resin removal step and the crystallizationstep was performed at atmospheric pressure (1.0×10⁵ Pa).

Comparative Example 2

Aluminum porous body No. 8 was produced as in Example 1, except that theheat-treatment temperature in each of the resin removal step and thecrystallization step was 600° C.

Comparative Example 3

Aluminum porous body No. 9 was produced as in Example 1, except that thepressure in each of the resin removal step and the crystallization stepwas 7.0×10⁻² Pa.

—Evaluation—

Aluminum porous body Nos. 1 to 9 provided above were evaluated asdescribed below.

Table 1 presents the evaluation results.

<X-Ray Diffraction>

Aluminum carbide in each of the aluminum porous bodies was detected witha SmartLab X-ray diffractometer available from Rigaku Corporation. Cu-Kαis used as an X-ray source. The excitation conditions of 45 kV and 40 mAwere used. The measurement range was 20=30° to 33°. The step size was0.04°. The counting time was 40 seconds. FIGS. 5 and 6 illustrate themeasurement results of aluminum porous body Nos. 2 and 8, respectively.In FIGS. 5 and 6, the vertical axis represents the diffraction intensity(counts per second: CPS), and the horizontal axis represents thediffraction angle 2θ(°).

Aluminum in each of aluminum porous body Nos. 1 to 9 was detected in ameasurement range of 2θ=37° to 40° at a step size of 0.04° and acounting time of 5 seconds.

<Aluminum Carbide Content>

The amount of aluminum carbide contained in each of the aluminum porousbodies was calculated from the ratio of the intensity of a peakoriginating from aluminum carbide to the intensity of a peak originatingfrom aluminum on the basis of the measurement results of XRD.

<Tensile Strength>

Autograph available from Shimadzu Corporation was used as a tensiletester. A test piece having a width of 20 mm and a length of 100 mm wascut from each aluminum porous body. A tensile test was performed at agauge length (length excluding tabs for gripping) of 60 mm when bothends are fixed by grips. The strain rate was 1 mm/min. Here, the tensilestrength referred to the maximum stress in the tensile test.

<Elongation at Break>

The term “elongation at break” used here referred to the percentage ofthe length L at which the maximum stress was observed relative to thegauge length in the tensile test above.

<Hardness H>

The hardness was measured with a nanoindenter.

<Number-Average Grain Size of Grains of Aluminum Layer>

The number-average grain size of the grains of the aluminum layer wascalculated by freely selecting 10 grains observed when a cross sectionof the skeleton of the aluminum porous body was observed with anelectron microscope (SEM) and averaging their grain sizes. When thenumber of grains observed in one field of view is less than 10,observation was continued in a different field of view to measure thegrain size of a total of 10 grains.

FIG. 7 is a photograph of a cross-section of the skeleton of aluminumporous body No. 2 observed with SEM. Portions enclosed by broken linesin FIG. 7 indicate grains of the aluminum layer.

TABLE 1 Evaluation Heat-treatment condition Number-average Aluminum incrystallization step Peak position 2Θ Aluminum Tensile Elongation grainsize of grain porous Pressure Temperature of aluminum carbide contentstrength at break Hardness of aluminum layer body No. (Pa) (° C.)carbide in XRD (°) (% by mass) (MPa) (%) (GPa) (μm) 1 1.0 × 10⁻² 66031.2 31.7 0.96 0.91 1.8 1.5 6.9 2 1.0 × 10⁻² 665 31.3 31.8 0.97 1.02 1.91.2 6.8 3 1.0 × 10⁻² 670 31.3 31.7 0.82 0.88 2.1 1.6 7.2 4 4.0 × 10⁻³660 31.2 31.7 1.01 0.98 2.0 1.5 6.9 5 1.0 × 10⁻² 660 31.2 31.7 0.92 0.952.0 1.5 7.1 6 1.0 × 10⁻² 660 31.2 31.8 0.99 0.92 1.9 1.6 6.9 7 1.0 × 10⁵660 — — — — — 8 1.0 × 10⁻² 600 31.5 0.94 0.51 1.1 0.4 1.8 9 7.0 × 10⁻²660 31.4 0.81 0.86 0.9 1.1 1.5

Because each of aluminum porous body Nos. 1 to 6 containedhigh-crystallinity aluminum carbide in the skeleton, peaks originatingfrom aluminum carbide were detected at two peak positions in a 2θ rangeof 30.8° or more and 31.5° or less and a 2θ range of 31.6° or more and32.3° or less in the XRD measurement. Additionally, each of aluminumporous body Nos. 1 to 6 had good results in terms of tensile strength,elongation at break, and hardness H (see Table 1).

In contrast, in aluminum porous body No. 7 produced by a conventionalproduction method, no peaks originating from aluminum carbide weredetected in the XRD measurement. It was impossible to measure elongationat break thereof.

In each of aluminum porous body No. 8 in which the temperature wasreduced in the resin removal step and aluminum porous body No. 9 inwhich the pressure of the atmosphere was increased, only one peakoriginating from aluminum carbide was detected in the XRD measurement.Both had lower elongation at break than aluminum porous body Nos. 1 to6.

REFERENCE SIGNS LIST

-   -   10 aluminum porous body    -   11 aluminum layer    -   12 skeleton    -   13 interior of skeleton    -   14 porous portion    -   15 resinous formed body    -   16 conductive layer

1: An aluminum porous body, comprising a skeleton with athree-dimensional network structure, wherein the skeleton is formed ofan aluminum layer containing aluminum carbide, and when the aluminumporous body is measured by an X-ray diffraction method, diffractionpeaks originating from aluminum carbide are detected at two peakpositions in a 2θ range of 30.8° or more and 31.5° or less and a 2θrange of 31.6° or more and 32.3° or less. 2: The aluminum porous bodyaccording to claim 1, wherein the skeleton has an aluminum carbidecontent of 0.5% or more by mass and 1.8% or less by mass. 3: Thealuminum porous body according to claim 1, wherein the aluminum porousbody has a tensile strength of 0.8 MPa or more. 4: The aluminum porousbody according to claim 1, wherein the aluminum porous body has anelongation at break of 1.6% or more. 5: The aluminum porous bodyaccording to claim 1, wherein the skeleton of the aluminum porous bodyhas a hardness H of 0.5 GPa or more and 2.0 GPa or less, the hardnessbeing measured with a nanoindenter. 6: The aluminum porous bodyaccording to claim 1, wherein grains in the aluminum layer constitutingthe skeleton have a number-average grain size of 2.0 μm or more and 10.0μm or less. 7: A method for producing the aluminum porous body accordingto claim 1, the method comprising: a conductivity-imparting treatmentstep of subjecting a surface of a skeleton of a resinous formed body toconductivity-imparting treatment to impart conductivity, the skeletonhaving a three-dimensional network structure; an electrolytic treatmentstep of subjecting the resinous formed body after theconductivity-imparting treatment step to electrolytic treatment in anelectrolyte solution to provide a resin structure throughelectrodeposition of aluminum on the surface of the skeleton; a resinremoval step of removing the resinous formed body to provide an aluminumporous body through removal of the resin structure by heat-treating theresin structure or by dissolving the resin structure with an acid or analkali; and a crystallization step, wherein the electrolyte solutionused in the electrolytic treatment step contains, as components: (A) analuminum halide; (B) one or more compounds selected from the groupconsisting of alkylimidazolium halides, alkylpyridinium halides, andurea compounds; and (C) an additive containing a carbon atom, theadditive being to be incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, wherein a molarmixing ratio of the component (A) to the component (B) is in a range of1:1 to 3:1, and each of the resin-removing step and the crystallizationstep is performed by heat-treating the resin structure in an atmosphereat 650° C. or higher and 680° C. or lower in a vacuum of 1.0×10⁻² Pa orless. 8: A method for producing the aluminum porous body according toclaim 1, the method comprising: a conductivity-imparting treatment stepof subjecting a surface of a skeleton of a resinous formed body toconductivity-imparting treatment to impart conductivity, the skeletonhaving a three-dimensional network structure; an electrolytic treatmentstep of subjecting the resinous formed body after theconductivity-imparting treatment step to electrolytic treatment in anelectrolyte solution to provide a resin structure throughelectrodeposition of aluminum on the surface of the skeleton; a resinremoval step of removing the resinous formed body to provide an aluminumporous body by removing the resin structure by heat-treating the resinstructure or by dissolving the resin structure with an acid or analkali; and a crystallization step, wherein the electrolyte solutionused in the electrolytic treatment step contains, as components: (A) analuminum halide; (B) one or more compounds selected from the groupconsisting of alkylimidazolium halides, alkylpyridinium halides, andurea compounds; and (C) an additive containing a carbon atom, theadditive being to be incorporated into aluminum electrodeposited on thesurface of the skeleton of the resinous formed body, wherein a molarmixing ratio of the component (A) to the component (B) is in a range of1:1 to 3:1, the resin removal step is performed by dissolution andremoval, and the crystallization step is performed by heat-treating theresin structure in an atmosphere at 650° C. or higher and 680° C. orlower in a vacuum of 1.0×10⁻² Pa or less. 9: A method for producing thealuminum porous body according to claim 1, the method comprising: aconductivity-imparting treatment step of subjecting a surface of askeleton of a resinous formed body to conductivity-imparting treatmentto impart conductivity, the skeleton having a three-dimensional networkstructure; an electrolytic treatment step of subjecting the resinousformed body after the conductivity-imparting treatment step toelectrolytic treatment in an electrolyte solution to provide a resinstructure through electrodeposition of aluminum on the surface of theskeleton; a resin removal step of removing the resinous formed body toprovide an aluminum porous body through removal of the resin structureby heat-treating the resin structure or by dissolving the resinstructure with an acid or an alkali; and a crystallization step, whereinthe electrolyte solution used in the electrolytic treatment stepcontains, as components: (A) an aluminum halide; (B) one or morecompounds selected from the group consisting of alkylimidazoliumhalides, alkylpyridinium halides, and urea compounds; and (C) anadditive containing a carbon atom, the additive being to be incorporatedinto aluminum electrodeposited on the surface of the skeleton of theresinous formed body, wherein a molar mixing ratio of the component (A)to the component (B) is in a range of 1:1 to 3:1, the resin removal stepis performed by heat-treating the resin structure at 400° C. or higherin an air atmosphere, and the crystallization step is performed byheat-treating the resin structure in an atmosphere at 650° C. or higherand 680° C. or lower in a vacuum of 1.0×10⁻² Pa or less.